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Specification Update 49
BV98. Performance Monitor Counters May Produce Incorrect Results
Problem: When operating with SMT enabled, a memory at-retirement performance monitoring
event (from the list below) may be dropped or may increment an enabled event on the
corresponding counter with the same number on the physical core’s other thread rather
than the thread experiencing the event. Processors with SMT disabled in BIOS are not
affected by this erratum.
The list of affected memory at-retirement events is as follows:
MEM_UOP_RETIRED.LOADS
MEM_UOP_RETIRED.STORES
MEM_UOP_RETIRED.LOCK
MEM_UOP_RETIRED.SPLIT
MEM_UOP_RETIRED.STLB_MISS
MEM_LOAD_UOPS_RETIRED.HIT_LFB
MEM_LOAD_UOPS_RETIRED.L1_HIT
MEM_LOAD_UOPS_RETIRED.L2_HIT
MEM_LOAD_UOPS_RETIRED.LLC_HIT
MEM_LOAD_UOPS_MISC_RETIRED.LLC_MISS
MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HIT
MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HITM
MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_MISS
MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_NONE
MEM_LOAD_UOPS_RETIRED.LLC_MISS
MEM_LOAD_UOPS_LLC_MISS_RETIRED.LOCAL_DRAM
MEM_LOAD_UOPS_LLC_MISS_RETIRED.REMOTE_DRAM
MEM_LOAD_UOPS_RETIRED.L2_MISS
Implication: Due to this erratum, certain performance monitoring event may produce unreliable
results when SMT is enabled.
Workaround: None identified.
Status: For the steppings affected, see the Summary Tables of Changes.
BV99. The Corrected Error Count Overflow Bit in IA32_ MC0_STATUS is Not
Updated After a UC Error is Logged
Problem: When a UC (uncorrected) error is logged in the IA32_MC0_STATUS MSR (401H),
corrected errors will continue to update the lower 14 bits (bits 51:38) of the Corrected
Error Count. Due to this erratum, the sticky count overflow bit (bit 52) of the Corrected
Error Count will not get updated after a UC error is logged.
Implication: The Corrected Error Count Overflow indication will be lost if the overflow occurs after an
uncorrectable error has been logged.
Workaround: None identified.
Status: For the steppings affected, see the Summary Tables of Changes.